Intracisternal A particles from FLOPC-1 BALB/c myeloma: presence of high-molecular-weight RNA and RNA-dependent DNA polymerase

The mouse plasmacytoma cell line, MOPC-460, produces both intracisternal and intracytoplasmic A-type particles when grown as a solid tumor. When these cells are grown either as an ascites tumor or in tissue culture, a third type of particle is produced extracellularly. This particle, the "myeloma-associated virus," is closely related to, and probably an alternate form of, the intracisternal A-type particle. The proteins present in these two types of particles were compared by tryptic peptide mapping. Both types of particles were found to contain essentially the same major proteins of 76,000 (p76), 68,000 to 70,000 (p68-70), and 45,000 (p45) daltons, in addition to varying amounts of smaller proteins. The relative proportions of all these proteins varied from preparation to preparation in an

supporting

confidence: 62%

Characterization of the proteins of intracisternal type A and extracellular oncornavirus-like particles produced by MOPC-460 myeloma cells

Robertson¹,

Jhabvala²,

Godefroy-Colburn³

et al. 1979

“…It is important to note that in all of these cases the A-particle-producing cells have been free of extracellular type C viruses (13, 33). On the other hand, significant sequence homologies between the nucleic acids of intracisternal A-particles, myeloma extracellular particles, MoMuLV, KiMuLV, and KiMSV have been reported by Robertson et al (23) and Krueger (11), respectively. In these studies the cDNAs used were generated by endogenous reactions with A-particle preparations from myelomas which were also producing extracellular viruses (11,23), and in one case intracytoplasmic type A-particles as well (23).…”

Section: Discussionmentioning

confidence: 95%

“…Intracisternal A-particles from mouse tumor cells share many properties with type B and C extracellular retroviruses, including the presence of high-molecular-weight polyadenylated RNA (11,16,22,34,35) and DNA polymerase (11,22,31,34,36). It is important to establish whether intracisternal A-particles have a genetic relationship with any of the RNA tumor viruses.…”

mentioning

confidence: 99%

“…It is important to establish whether intracisternal A-particles have a genetic relationship with any of the RNA tumor viruses. However, tests for sequence homology between A-particle RNA and the RNAs of other viruses have given somewhat conflicting results (11,17,23,34,37). A major problem in many of these studies has been the uncertainty that the RNAs and the complementary DNAs (cDNAs) used were specific for and representative of the Aparticle genome.…”

mentioning

confidence: 99%

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Genetic individuality of intracisternal A-particles of Mus musculus

Lueders¹,

Kuff²

1979

The nucleic acid sequence relationship between mouse intracisternal type A-particles and type C and B viruses was examined by reciprocal complementary DNA-RNA hybridization; complementary DNAs prepared from the RNAs of intracisternal A-particles were hybridized with high-molecular-weight RNAs from a variety of murine tumor viruses, and complementary DNAs representing a variety of RNA tumor virus genomes were hybridized with the high-molecular-weight RNAs from A-particles. The criterion for homology between two types of virus was that the heterologous hybridization reaction occurs over the same RNA concentration range as the homologous reacton. The results of these hybridizations indicate that there are no major sequence homologies between the RNA of intracisternal A-particles and the RNA of representative members of type B and C viruses of Mus musculus.

“…Intracisternal A-type particles are commonly found in a variety of transformed mouse cells and occasionally in normal mouse cells (33), and they have been present in every plasmacytoma ("myeloma") so far examined (22,31). They resemble cores of immature Bor C-type viruses and contain high-molecular-weight (60 to 70S) RNA and RNA-dependent DNA polymerase (18,24, 26, [34][35][36]. Moreover, complementary DNA (cDNA) probes prepared from MOPC-460 plasmacytoma A-type particles show considerable homology (-30%) to the genome of Moloney murine leukemia virus (MuLV) (24,26), and the major protein present in these particles (p76) has recently been found to be immunologically related to p30 from AKR MuLV (25).…”

mentioning

confidence: 99%

Characterization of infectious oncornaviruses from MOPC-460 plasmacytomas: their relation to A-type particles

Ramabhadran¹,

Hartley²,

Rowe³

et al. 1979

MOPC-460 mouse plasmacytoma cells produce intracellular A-type particles and extracellular oncornavirus-like particles ("myeloma-associated virus," abbreviated MAV). The genomes of these two particles are closely related. During attempts to establish infections with MOPC-460 extracellular particles, we isolated ecotropic and xenotropic infectious forms of murine leukemia virus. We have investigated the relation of these isolates to A-type particles and to MAV by nucleic acid hybridization. Using complementary DNA probes prepared from the two isolates, we found that these infectious murine leukemia viruses differ from A-type particles and from MAV. Moreover, we found that MAV is the predominant extracellular component: the ecotropic and xenotropic forms of murine leukemia virus were present at only low levels (<5%) in MAV preparations. Neither the SC-1 cells infected with ectropic murine leukemia virus nor the mink cells infected with xenotropic murine leukemia virus showed any A-type particles in their cytoplasm when examined by electron microscopy. Our inability to demonstrate infection by the A-type particle-related component, MAV, suggests that these may be defective.